By introducing scalar potential functions

Helmholtz decomposition theorem and Fourier transform technique

the three dimensional transmission of vibrations over the surface of the ground

due to a harmonic rectangular moving load

is investigated theoretically; and it is accordant with the practice. The material of subgrade

obeying Biot’s dynamic poroelastic theory

is idealized as a uniform

fully saturated poroelastic layer of soil stratum. The analytical solutions of stress

displacement and pore pressure are obtained in the form of integral. Numerical results are obtained by inversing the Fourier transform and are used to analyze the influence of the moving load velocity on the vertical displacement on the surface of the ground and the distribution of pore pressure along the arbitrary depth of ground. It is shown that the displacement amplitude increases with the increasing of the load velocity and there is great difference for the distribution of the pore pressure along the depth of the foundation at different point of rectangular moving load.